Most members of the family Theridiidae have a "comb" of
serrated bristles on the last segment (tarsus) of the fourth leg.
The comb helps to draw sticky threads of silk from the spinnerets
to wrap any prey caught in the web.

When the victim is securely
enveloped in silk, the spider will then approach it and bite through the
silky bundle, extinguishing any further signs of struggle. The snare is
an irregular three-dimensional structure.